kernel: Eliminate kernel global state

As means to pave the way for getting rid of global state within core,
This eliminates kernel global state by removing all globals. Instead
this introduces a KernelCore class which acts as a kernel instance. This
instance lives in the System class, which keeps its lifetime contained
to the lifetime of the System class.

This also forces the kernel types to actually interact with the main
kernel instance itself instead of having transient kernel state placed
all over several translation units, keeping everything together. It also
has a nice consequence of making dependencies much more explicit.

This also makes our initialization a tad bit more correct. Previously we
were creating a kernel process before the actual kernel was initialized,
which doesn't really make much sense.

The KernelCore class itself follows the PImpl idiom, which allows
keeping all the implementation details sealed away from everything else,
which forces the use of the exposed API and allows us to avoid any
unnecessary inclusions within the main kernel header.

1 files changed, 84 insertions, 5 deletions

diff --git a/src/core/hle/kernel/kernel.h b/src/core/hle/kernel/kernel.h
index 131311472..089e959ac 100644
--- a/src/core/hle/kernel/kernel.h
+++ b/src/core/hle/kernel/kernel.h
@@ -4,14 +4,93 @@
 
 #pragma once
 
-#include "common/common_types.h"
+#include "core/hle/kernel/object.h"
+
+template <typename T>
+class ResultVal;
+
+namespace CoreTiming {
+struct EventType;
+}
 
 namespace Kernel {
 
-/// Initialize the kernel with the specified system mode.
-void Init();
+class HandleTable;
+class Process;
+class ResourceLimit;
+class Thread;
+class Timer;
+
+enum class ResourceLimitCategory : u8;
+
+/// Represents a single instance of the kernel.
+class KernelCore {
+public:
+    KernelCore();
+    ~KernelCore();
+
+    KernelCore(const KernelCore&) = delete;
+    KernelCore& operator=(const KernelCore&) = delete;
+
+    KernelCore(KernelCore&&) = delete;
+    KernelCore& operator=(KernelCore&&) = delete;
+
+    /// Resets the kernel to a clean slate for use.
+    void Initialize();
+
+    /// Clears all resources in use by the kernel instance.
+    void Shutdown();
+
+    /// Provides a reference to the handle table.
+    Kernel::HandleTable& HandleTable();
+
+    /// Provides a const reference to the handle table.
+    const Kernel::HandleTable& HandleTable() const;
+
+    /// Retrieves a shared pointer to a ResourceLimit identified by the given category.
+    SharedPtr<ResourceLimit> ResourceLimitForCategory(ResourceLimitCategory category) const;
+
+    /// Retrieves a shared pointer to a Thread instance within the thread wakeup handle table.
+    SharedPtr<Thread> RetrieveThreadFromWakeupCallbackHandleTable(Handle handle) const;
+
+    /// Retrieves a shared pointer to a Timer instance within the timer callback handle table.
+    SharedPtr<Timer> RetrieveTimerFromCallbackHandleTable(Handle handle) const;
+
+    /// Adds the given shared pointer to an internal list of active processes.
+    void AppendNewProcess(SharedPtr<Process> process);
+
+private:
+    friend class Object;
+    friend class Process;
+    friend class Thread;
+    friend class Timer;
+
+    /// Creates a new object ID, incrementing the internal object ID counter.
+    u32 CreateNewObjectID();
+
+    /// Creates a new process ID, incrementing the internal process ID counter;
+    u32 CreateNewProcessID();
+
+    /// Creates a new thread ID, incrementing the internal thread ID counter.
+    u32 CreateNewThreadID();
+
+    /// Creates a timer callback handle for the given timer.
+    ResultVal<Handle> CreateTimerCallbackHandle(const SharedPtr<Timer>& timer);
+
+    /// Retrieves the event type used for thread wakeup callbacks.
+    CoreTiming::EventType* ThreadWakeupCallbackEventType() const;
+
+    /// Retrieves the event type used for timer callbacks.
+    CoreTiming::EventType* TimerCallbackEventType() const;
+
+    /// Provides a reference to the thread wakeup callback handle table.
+    Kernel::HandleTable& ThreadWakeupCallbackHandleTable();
+
+    /// Provides a const reference to the thread wakeup callback handle table.
+    const Kernel::HandleTable& ThreadWakeupCallbackHandleTable() const;
 
-/// Shutdown the kernel
-void Shutdown();
+    struct Impl;
+    std::unique_ptr<Impl> impl;
+};
 
 } // namespace Kernel